Improvement in valve-gear for steam-engines



UNITED STATES PATENT OFFICE.

EDWIN SPRAGU, OF ALLEGHENY, PENNSYLVANIA.

IMPROVEMENT IN VALVE-GEAR FOR STEAM-ENGINES.

Specification forming part of Letters Patent No. 55.73 l, dated June 19,ISGS.

To all whom fit may concern:

Be it known that I, EDWIN SPRAGUE, of the city and count-yof Allegheny',in the State of Pennsylvania, have invent-ad a new and usefulImprovement in Steam-Engines; and I do hereby declare that the followingis a full and exact description thereof, reference being had to theaccompanying drawings, and to the letters of reference marked thereon.

The. nature of my invention consists in the use of an adjustable pointin connection with a cam, cam-yoke, cam-rod, and hinged lifters on therocking shaft, which lifters are. held in their working position bymeans of triggers which are operated by means ofinclined planes, saidadjustable point, cam, canryoke, canrrod, hinged lifters, triggers, andinclined planes being used in connection with the valveAlevers ofsteanrengines for the purposel of opening` the steam valves or ports andclosing them at any desired point in the stroke of the engine,

ythe wholebeingconstructed, arranged, and operating in the mannerhereinafter described.

To enable others skilled in the art to make and use myinvention, l willproceed to describe its construction and operation.

In theaccompanying drawings, Figure 1 represents a side elevation of anexigirlefurnished with my improvement for operating the valves. Fig. 2represents a plan or top view ofthe same. Fig. 3 represents the sidepipe, and also represents the hinged lifters, triggers, inclined planes,and the relation these parts bear to the lever to which the valve-stemsare attached. Fig. 4 represents a top view or plan ofthe in clinedplanes, their guide, and the lever for operating them. A

In thedrawings, Arepresents the base or bed for the engine. B representsthe cylinder. C represents the side pipe. e represents the standardswhich act as the fulcrum for the levers fi, to which the stems g of thevalves are attached. 6 represents the piston. It represents the Thead,to which the pitman, marked 7 is attached. 9 represents the crank, whichis secured on the end of the shaft 16. 15 re p resents the cam-yoke. 14represents the guides for the cam yoke. 5 represents the slides for theT-head R. 10, 11, and 12 represent the cam-rod, which is attached to thecani-yoke 15.

8 represents the rock-shaft, on the end of which is placed theshifting-lever, marked j, which is furnished with wrists, marked lc andl.

All of the parts above mentioned are of ordinary construction, andtheirarrangeinent and use are well understood. I will therefore proceedto describe the parts which constitute my invention and their relationto the parts as above mentioned.

The cam marked 1S is secured on the shaft 16, and is what is termed afull-stroke77 cam. This cam is furnished with a slot, marked 20. Ou the.shaft 16 is also placed what I shall term an adjustable point.77 Thispointis marked 17, and is arranged on the shaft I6, in close contactwith the cam 1S, and is so arranged on the shaft 1G and with relation tothe cam that it can be secured to the cam 1S at any' point desired bymeans of a set-screw, which can be moved back and forward in the slot2() of the cam 1S.

19 represents a spring which is used for holding the canryoke 15 incontact with the cam 1S and the adjustable. point 17. The arrangement ofthis spring will readily be seen by a reference to Fig. 1. in the,drawings, and it will readily he observed by the skillful mecha-nic thatother arrangements of spring or other device can be substituted forholding the camyoke in contact with the cam and point.

On the rock-shaft S is secured a piece, marked p, to which. are securedlifters, marked a, which are hinged at the point marked c. To lthe piecemarkedp are also secured two triggers, marked r, which have two armseach. One of these arms on each of the triggers connects with the lowerarm of the lifters n, and the other arms act on the inclined planesmarked 1.

The form and arrangement of the lifters u, triggers r,'and inclinedplanes '1, and the relation that theyT bear to each other, are clearlyshown in Fig. 3. The inclined planes marked 1 are se' cured on a plate,marked y, which moves in a guide plate, marked 4, or between guides,marked el, as shown in Figs. 3 and 4. These guides 4 are secured on theside pipe, C, and are so arranged with relation to the plate y as tobring the inclined planes directly under the lower arms of the triggersr. To the plate y is attached a lever, marked o, which is secured to theside pipe, O, and has its fulcrum at 0. The leyero is furnished with anindex-pointer,

marked t, which is used in connection with a scale, marked a0, to showat what point the steam is cut off'.

The lever ois used when a number ofinclined planes of different heightsare used, so that the cut-oft may be used in connection with thegovernor ot' engines, as indicated by the parts marked fw, which isattached to the governor so that it can move up and down with the riseand fall ot' the governor-balls. Thepart marked 'L0 moves in guides, asindicated by the parts marked 22, and the lower part of the part w isfurnished with a slot, marked 21, which runs obliquely to the plane ot'the part marked w. In this slot is placed the point marked 2 of thelever o. Now, every ehangein the position oft-he governor-balls willchange the position of the plate y, and thereby bring a differentinclined plane under the lower arms ot' the triggers o",

and thereby cause a difference in time of the triggers holding thelitters a in a lifting position. It will be observed that but twoinclined planes are represented in the drawin gs-one for each trigger;but, as already stated, a number of these inclines may be placed side byside, so that each trigger shall have a series ot' inclines and all madeoperative through lever 0 and plate y.

The lever o, in connection with the plate y, is also used for thepurpose ot giving the engine full stroke. This is accomplished by somoving the lever o and plate y that the lower arms of the triggers rwill not come in Contact with the inclined planes 1.

The reverse action or motion is given to the engine by unshipping thecam-rod from oft' wrist Zand shipping it ou the wrist k.

The cam-rod can be made in one or more parts, as desired, and its lengthadjusted by any of the known means. In the drawings the cam-rod isrepresented in three parts-to wit, 10, 11, and 12-and the parts 11 and12 attaehed to an upright, marked 13, which will have a vibrating motionwhen the engine is working. The cam-rod is represented as being adjustedby means of a set-screw, marked Q2, which mode of adjustment willreadily be understood by reference to Fig. 1.

The operation of my improvement is as follows: I set the adjustablepoint 17 on the cam 18, so as to get the desired stroke of the camrodwhich will give the desired movements to the lever j and rock-shaft 8,which will move the piece p, which will cause the lifters n to come inContact with the levers i, which will lift the valves and admit steam tothe cylinder; and the lower arms of the triggers will come in contactwith the inclines marked l, which will cause the triggers to unship andlet the litters drop down on the pieces marked 3, which will close thevalves by the dropping of levers fi. As one of the triggers r becomesunshipped the other becomes shipped. The steam is exhausted in theordinary manner.

Having thus described my invention, what I claim is- 1. The hingedlitters n, said lifters being operated by mea-ns ot' triggers r andinclines l, or their equivalents, and one cam-rod made in one or moreparts, said litters, triggers, inclines, and cam-rod being dependent fortheir action upon the cam 18 and adjustable point 17, substantially asherein described and set forth.

2. The adjustable point 17,when used in com; bination with a cam andcam-yoke and a single cam-rod for working a full stroke, and used foroperating the cut-oft' gear of steam-engines, as herein described andset forth.

3. rIhe inclines 1 on plate y, said plate and inclines being operated bylever o through the medium ot' a governor or otherwise, substantially asherein described, and for the purpose set forth.

EDWIN SPRAGUE. Witnesses:

JAMES J. JOHNSTON, ALEXANDER HAYs.

